1.取出List里面Id的集合可以用stream这样操作：
Function<Map<String,object>,String> applyAssetFunction = applyAsset ->{
String objectId = (String)applyAsset.get(ClassNameCons.DATA_ENTITY.REF_DATA_OBJECT);
String mobjectId = (String)applyAsset.get(ClassNameCons.DATA_ENTITY.REF_M_DATA_OBJECT);
return StringUtils.isEmpty(ObjectId)?objectId:mobjectId
}
List dataObjectIds = assetInfoList.stream().map(applyAssetFunction).filter(item->!StringUtils.isEmpty(item)).collect(Collectors.toList)
2.取出list对象里面的某个字段的集合；
JSONArray devArrays = JSONObject.parseArray(devOffice);
List devUserList = devArrays.stream.map(obj ->(String)(JSONObject)obj).get("targetId")).collect(Collectors.toList());
3.Stream判断list里面是否有相关参数；返回boolean类型
boolean flag = applyApproveFlowListquery.stream().filter(ApplyApproveFlow ->"reject".equals(applyApproveFlow.getApproveOption())).findAny().ispresent();
4.Stream根据id进行去重
Stream wfProcessInstanceDTOStream = content.parallelStream().filter( (WfProcessInstanceDTO::getId)); List result = wfProcessInstanceDTOStream.collect(Collectors.toList());
5.stream去除重复对象的方法
List addNodeSetCollect = wfNodeSetList.stream().filter(item -> wfNodeSets.stream().noneMatch(tmp -> tmp.getProcTaskKey().equals(item.getProcTaskKey()))).collect(Collectors.toList()); List deleteNodeSetCollect = wfNodeSets.stream().filter(item -> wfNodeSetList.stream().noneMatch(tmp -> tmp.getProcTaskKey().equals(item.getProcTaskKey()))).collect(Collectors.toList());
6.Stream根据时间进行排序；
Stream sorted = content.stream().sorted(Comparator.comparing(WfProcessInstanceDTO::getTranspondTime)); List collect = sorted.collect(Collectors.toList());
7.元素逆序
list.stream().sorted(Comparator.comparing(Student::getAge).reversed())
